GB447044A - Improvements in or relating to the drying of materials - Google Patents

Abstract

447,044. Drying plaster board &c. SPOONER, W. W., Ashbrook Grove Road, Ilkley, Yorkshire. Oct. 10, 1934, Nos. 28971/34 and 306/35. [Classes 34 (i) and 34 (ii)] Relates to the drying o: relatively thick materials which are apt to dry or the surface before the dry ing of the interior is com pleted, such as plaster board, and consists in sub jecting the materials at an interval or intervals ir the process of drying, and preferably, also prior to the commencement of dry ing, to the action of satur ated or unsuperheatec steam or vapour, to heat the material without effecting any substantial drying thereof. Preferably, such heating is substantially to the boiling point of the liquid to be evaporated. A suitable steaming unit comprises nozzles 10, Fig. 2, continuous transversely of material fed between upper and lower casings. To prevent drip on to the upper surface of the material, steam reaches the nozzles by a narrow passage between walls 16, 17 adjacent to which are gilled heater tubes 18. The outermost nozzle is prevented from cooling by a steam pipe 15. A fan may have its suction side connected to the space between the casings and deliver to the casings. Alternatively, a conveyer may carry material between upper and lower chambers 35, 33, Fig. 4, nozzles 34 directing steam on to the material, the fluid being drawn into the chamber 35 and so kept in circulation, heating pipes 37 maintaining the desired temperature. The circulating fan for the drying portion of the apparatus may have a separate element for drawing in fresh air. Superheated steam may be used for the drying. In a modification, material to be dried may be placed in a suitable casing through which fluid is circulated in closed circuit, the fluid being alternately a saturated and a drying fluid. The material 50, Fig. 8, rests on rods 51 above nozzles 55 on a pressure chamber 53, an apertured diaphragm above the material constituting the floor of a suction chamber. Fluid is circulated by a fan 58, a steam supply pipe 68 and adjustable air inlet slide 63 being provided. Steam heating pipes 64 are placed in the passage between the chambers, and valves may be operated by a suitable time control to change the character of the fluid from dry to saturated. Specification 422,117, [Group IV], is referred to.